oracle中Listener中rate_limit參數的一些說明

（一）參數說明：

（1）. rate_limit參數從9.2.0.8引入，可以用來控制串連風暴。rate_limit後面跟的參數是允許每秒串連的個數，配置完成後，需要stop/start listener生效。如下：

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = host.sample.com)(PORT = 1521)(RATE_LIMIT=5))
    )
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = host.sample.com)(PORT = 1522))
    )
   )

上面的配置表示1521連接埠只允許每秒5個串連，而1522連接埠是沒有限制的。

配置以後，在listener.log中，如果有超過設定的串連數，會報錯tns-1158：
在11：42：24這個時刻，可以看到最多5個串連，超出的就報錯tns-1158了。

15-MAY-2010 11:42:24 * establish * 1158
 
TNS-01158: Internal connection limit reached, preventing dispatcher from connecting
 
15-MAY-2010 11:42:24 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=S111W6)(CID=(PROGRAM=sqlplus)(HOST=sample.com)(USER=grdbms))) * (ADDRESS=(PROTOCOL=tcp)(HOST=sample.com)(PORT=60340)) * establish * S111W6 * 0
 
15-MAY-2010 11:42:24 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=S111W6)(CID=(PROGRAM=sqlplus)(HOST=sample.com)(USER=grdbms))) * (ADDRESS=(PROTOCOL=tcp)(HOST=sample.com)(PORT=60341)) * establish * S111W6 * 0
 
15-MAY-2010 11:42:24 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=S111W6)(CID=(PROGRAM=sqlplus)(HOST=sample.com)(USER=grdbms))) * (ADDRESS=(PROTOCOL=tcp)(HOST=sample.com)(PORT=60342)) * establish * S111W6 * 0
 
15-MAY-2010 11:42:24 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=S111W6)(CID=(PROGRAM=sqlplus)(HOST=sample.com)(USER=grdbms))) * (ADDRESS=(PROTOCOL=tcp)(HOST=sample.com)(PORT=60344)) * establish * S111W6 * 0
 
15-MAY-2010 11:42:24 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=S111W6)(CID=(PROGRAM=sqlplus)(HOST=sample.com)(USER=grdbms))) * (ADDRESS=(PROTOCOL=tcp)(HOST=sample.com)(PORT=60343)) * establish * S111W6 * 0
 
15-MAY-2010 11:42:25 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=S111W6)(CID=(PROGRAM=sqlplus)(HOST=sample.com)(USER=grdbms))) * (ADDRESS=(PROTOCOL=tcp)(HOST=sample.com)(PORT=60345)) * establish * S111W6 * 0
 
15-MAY-2010 11:42:25 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=S111W6)(CID=(PROGRAM=sqlplus)(HOST=sample.com)(USER=grdbms))) * (ADDRESS=(PROTOCOL=tcp)(HOST=sample.com)(PORT=60346)) * establish * S111W6 * 0
 
15-MAY-2010 11:42:25 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=S111W6)(CID=(PROGRAM=sqlplus)(HOST=sample.com)(USER=grdbms))) * (ADDRESS=(PROTOCOL=tcp)(HOST=sample.com)(PORT=60347)) * establish * S111W6 * 0
 
15-MAY-2010 11:42:25 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=S111W6)(CID=(PROGRAM=sqlplus)(HOST=sample.com)(USER=grdbms))) * (ADDRESS=(PROTOCOL=tcp)(HOST=sample.com)(PORT=60349)) * establish * S111W6 * 0
 
15-MAY-2010 11:42:25 * (CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=S111W6)(CID=(PROGRAM=sqlplus)(HOST=sample.com)(USER=grdbms))) * (ADDRESS=(PROTOCOL=tcp)(HOST=sample.com)(PORT=60348)) * establish * S111W6 * 0

（2）. 除了上面的這種配置，還有另外一種配置方式，設定connection_rate_listener

 LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = host.sample.com)(PORT = 1521)(RATE_LIMIT=YES))
    )
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = host.sample.com)(PORT = 1522)(RATE_LIMIT=YES))
    )
  )
CONNECTION_RATE_LISTENER=10

上述配置表示1521和1522連接埠，都受到rate_limit的限制，每秒最多串連數是10個。

（二）已知問題

（1）. Bug 8529537 : ALL NEW CONNECTIONS ARE REFUSED BY ORA-12547 AFTER TNS-01158 IN LISTENER.LOG
描述：當達到設定rate_limit的最大值之後，報錯tns-1158，但是後續新的串連無法串連了。
受影響版本：11.2.0.1、11.1.0.7、10.2.0.4
Fix版本：11.2.0.2 、 12.1

（2）. Bug 16409926：LISTENER MEMORY LEAK IF RATE_LIMIT IS USED AND ENFORCED FREQUENTLY
描述：設定rate_limit之後，過來的串連需要花費較長的時間才能建立，tnsping的響應也需要較長時間，重啟listener之後可以解決問題，但是不久之後問題重現。
受影響版本：11.2
Fix版本：11.2.0.4 and 12.1.0.2，或者應用patch 16409926。